#12203: Allow constructors on LHS of (implicit) bidirectional pattern synonym -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: feature request | Status: new Priority: low | Milestone: Component: Compiler (Type | Version: 8.0.1 checker) | Keywords: Resolution: | PatternSynonyms Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by mpickering): It seems like quite a big change to me to specify the expression rather than the pattern. It also raises questions in the case of explicitly bidirectional pattern synonyms, do you specify two expressions? One which gets actually converted to a pattern and one which actually gets used in expressions? What about for implicitly bidirectional pattern synonyms do we still specify an expression on the RHS? Still quite tricky with some details to be worked out! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12203#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler